Means and method of secret transmission of signals



June 9, 1931.

c. SCHAPIRA MEANS AND METHOD OF SECRET TRANSMISSION SIGNALS Filed July 1. 1927 CHRL SCHAHRA BY (2m @dm ORNEY Patented June 9, 1931 UNITED STATES PATENT OFFICE CARL SCHAPIRA, OF IBERIIN', GERMANY, ASSIGNOR TO GESEILSGHAFT F'il'R DRAHT- LOSE TELEGRAPHIE M. B. H., OF BERLIN, GERMANY, A CORPORATION OF GERMANY MEANS AND METHOD OF SECRET TRANSMISSION OF SIGNALS Application filed July 1, 1927, Serial No.

The invention relates to an arrangement adapted for the transmission of code signals or telephonic conversation in such a way that third parties not possessing thedeciphering or decoding device will be unable to understand the same. As one embodiment of the invention, a steel tape or band, such as used in a telegraphone, may be impressed with the signal or speech records and a transmitting device connected thereto modulated by the corresponding signal or speech frequencies. However modulation, is not eflected directly, but rather by means of an action adapted to render the signals or speech unintelligible in a normal receiver.

In one embodiment of the present invention the signals or speech is subdivided into portions or sections; however, the latter are not mixed together or intermingled as in known methods, but they are tra'nsmittedin their normal sequence. However, according to this invention, each such subdivision or section is run ofi separately and inverted while at the receiving station, by using a similar device working in synchronism with the sending device, each of these sections is again inverted and thus fed to the receiver so that the original signals or speech is reproduced.

In the accompanying drawin the figure.

shows diagrammatically one em odiment of the invention. At the sending station is mounted a unit comprising two rollers or pulleys 1 and 2 which may be rotated by a motor or other desired means. These pulleys carry an endless band 3 of magnetic material such as iron or steel, this band, serving as a recording medium on which impressions corresponding to the signals are made. As one means for impressing the signals on the band 3 I show an electromagnet 4 actuated by an amplifier 6 the current of which is modulated by microphone 5; however, I may .use any other desired means for impressing the signals or speech frequencies on the recording medium. The signals may be extinguished after being used by any desired means, an electro-magnet 7, being shown. Over rollers 8, 9 and 10, mounted adjacent rollers 1 and 2, travels a second endless band 11 which carries the take-ofi or pick-up magnets 12, 13

202,835, and in Germany July 16, 1926.

and 14. Now while the band 3 travels continuously at substantially a constant speed, the band 11 is arranged to travel in the same direction at about twice that speed so that the text of each section of the signals or message is taken up in reverse order or inverted at normal speed by one of the magnets carried on band 11. Any desired means may be used to drive band 11 at the proper speed. Magnets 12, 13 and 14 are so mounted on the band 11 that, when one of themleaves the band 3, the next magnet enters thereon with the result that the respective sections of the signals or conversation are placed end to end. The connections of the magnets 12, 13 and 14 may be brought to slip rings 15 by way of suitable brushes or mercury contacts. It will be understood that, for instance, in the transmission of the word telefunken the magnet 12 takes OK this word in phonetic inversion and thus applies it to any suitable device 16 which serves to transmit the inverted word to the receivingstation. In the same way the following word will be taken ofi' by the magnet 13 and reproduced.

For decoding the message similar moving bands and magnets are used at the receiving station, corresponding parts being primed. An electro-magnet 17 connected to a circuit 18 serves to impress the inverted signals on steel band 3, current being supplied in circuit 18 by transmitting device 16 in any suitable. manner by either wire or wireless connection, a wired connection being shown simply by way of illustration. The receiving device including band 11', magnets 12', 13, 14' and slip rings 15. serves to pick up the inverted sections of the message or signals from band 3'. Any suitable type of translating device may be connected to slip rings 15 to receive the message, that shown being a telephone receiver 19.

As an illustration of the method of operation of applicants device, if it is desired to transmit a signal consisting of the characters abcdefghij kl,itmaybcrecordedin four groups of 3 letters each the letters of each group being recorded in normal order by magnet 4 on hand 3. After lettersa b chave been recorded the portion of band carrying them will be in the bottom position moving adjacent magnet 12 which due to its higher speed will pick up the letters in the inverted orderc b a-in which order they will be lead to transmitter 16 and transmitted. It is to be noted that not only is the order of the letters a b c inverted but that also the letter itself is inverted. Taking the Morse code as an illustration the signal would be put on as dotdash; dashdotdot-dot; dashdot-dash-dot and when inverted would appear as dot -dashdot dash dot dot dot dash dash dot. While this group of letters is being trans: mitted the next groupd e fwill be recorded on hand 3 by magnet 4 in normal order and when the portion of band 3 on which they are recorded reaches the bottom position, magnet 13 will pick up the letters in inverse order and the group will be transmitted in the sequencef e (1.

After these letters have been removed from the band by magnet 7, the next group will be impressed in normal order-g h iand picked up by magnet 14 and transmitted in inverse order--i h g-. The last group will be similarly transmitted in inverse order as l k jso that the signal will be transmitted in the sequence'c b a, f e d, i h g, l lr j-in which sequence it will be impressed on band 3' by magnet 17. The magnets carried by band 11' then pick up the letters of each group in inverse order so that the signal is impressed on phone 19 in its original, normal order.

It will be understood that for the proper operation of the transmission system the units at the sending and receiving stations are suitably connected to operate in synchronism, for example by having the driving motors of the respective units properly connected for synchronous operation. However, the partlcular means for causing the synchronous operation is not a part of my invention and I may use any preferred means for efi'ecting the desired result. Also, conversation in both directions simultaneously is feasible b mounting two such devices at both the sen ing and receiving stations;

While I have herein shown a particular embodiment of my invention, I do not limit myself to the form shown but what I desire to secure by Letters Patent is:

1. In an apparatus for transmitting a series of normally arranged signals, a recording medium, means for impressin the signals on said medium in normal or er, a second recording medium, means coacting with each recording medium and arranged to transfer to the second the signal impressions on the first in inverted order, and means coacting with the second recording medium adapted to re-arrange said signals in normal order.

2. In an apparatus for transmitting a series of consecutively arranged signals, a recording medium, means for impressing the tive portions of said band magnetic conditions corresponding in sequence to the signal sequence, a second hand of magnetic material, a transmission device coacting with each band and arranged'to transfer to the second hand the magnetic conditions of the first band in an inverse order, and means coacting with the second band arranged to pick up the inverted signals and reproduce them in their normal order.

4. In an apparatus for transmitting normally arranged signals, a moving band of magnetic material, means for establishing in said band magnetic conditions corresponding to the signals, a second moving band of magnetic material, a moving electro-magnet associated with the first band arranged to pick up the magnetic impressions thereon in reversed order, means connected to said elecire-magnet and arranged to transfer said impressions to the second hand, a receiver, and a moving electro-magnet connected to the receiver and arranged to pick up the magnetic impressions of the second hand in their original order.

5. In apparatus for secret signalling, means for consecutively recording said signals in their normal order, means for subdividing said signals into a predetermined number of groups and means for picking up the signals of each group in an inverted order.

6. In a device for transmitting a series of consecutively arranged signals, a recording medium, means for impressing on consecutive portions of said medium magnetic conditions corresponding in order to the original signals and means mounted adjacent said medium and movable with respect to said medium, arranged to be influenced by said magnetic conditions in a reversed order.

7. In a device for transmitting a series of consecutively arranged signals, a movable recording medium, means for impressing on said medium magnetic conditions corresponding to and in the same sequence as the signals and a movable magnet arranged to be influenced b said magnetic conditions in a reversed or er.

8. In a secret signalling system, a movable recording medium, means for impressing on said medium magnetic conditions corresponding to and in the same sequence as the signals, a magnetically responsive means mounted adjacent said medium and means for moving said lattermeans at as eed greater than that of said recording m um and in such direction as to be influenced-by said magnetic conditions in an inverted order.

9. In a secret signalling system, a movable band carrying magnetic impressions, a second band, means for moving said second band in the same direction of travel and at a speed greater than the speed of said first bandand a magnetically responsive device carried by said second band arranged to be influenced by the magnetic impressions of the first band.

10. The method of transmitting intelligence which comprises making a record of the signals or messages, picking up the signals from the record in the reverse order to which they were recorded, transmitting the signals or messages so picked up to a distant point and there restoring them to their original form.

-11. The method of transmitting intelligence which comprises makin a record of the signals or messages at a efinite speed,

picking up the signals or messages from said record at a di-flerent speed from and in the reverse order to that in which they were recorded, transmitting the signals or messages so picked up to a distant point and there restoring them to their ori inal form.

12. The method of transmitting intelligence which comprises recording the signals or messages upon a moving body, picking up said signals or messages from said body 3 by means of a second body which moves in the same direction as and at a greater speed than the first-mentioned'body, transmitting the signals or messages so picked up to adistant point and there restoring them to their 40 original form.

CARL SCHAPIRA. 

